I use an RME Multiface and it works well. I've never used Pro Tools before but from what I can gather, Pro Tools makes their own PCI cards which have some Motorola chips on it for audio processing.
I read somewhere that there's basically 0 latency when using a Pro Tools rig and I'm guessing that's because of the PCI cards handling the processing and not your native CPU. Now whether the processing is for just D/A and A/D conversion, or just plugins processing, or both, and whether the plugin processing feature is available only for Pro Tools and not Logic I'm unsure.
Would there be any benefit as far as latency/speed of getting some older Pro Tools hardware for use in Logic? If there's no benefit of that, and I could only get the benefit by using Pro Tools, then maybe I could run a hybrid Logic/Pro Tools setup so I can compose in Logic, then mix in Pro Tools.
But maybe there's no benefit at all. Someone give me the lowdown